The field of the present invention relates generally to scanners. More particularly, it relates to systems, methods, and apparatus for improving the scanning performance of imaging scanners.
Imaging technology provides a number of benefits relative to more conventional laser scanning. For example, imagers are able to capture information at a much higher data rate than laser scanners. This provides for an earlier first opportunity for a label read, a denser effective scan pattern, and more scanning opportunities over a given time span. These advantages typically speed up the overall operation of the scanner in comparison with laser scanners. Imaging also may provide lower costs and higher reliability than laser scanning, which is a distinction that is likely to become more significant over time as imager costs continue to decline.
However, there are a number of drawbacks to imaging scanners. Many current laser-based fixed scanners utilize facet wheels and mirror baskets to create a scan pattern that gives scan coverage over a large spatial volume. This large scan volume allows a barcode to be read on any of several different scan lines having different viewing angles. Imaging scanners, by contrast, are typically based on a single lens and single imager array. Such scanners therefore provide only a single point of view, which may limit the ability of the scanner to recognize a barcode in certain circumstances.
For example, because the scan volume of an imaging scanner is conical in shape, attempting to read a barcode or other image in close proximity to the scanning window (reading “on the window”) may be less effective than with a basket-type laser scanner. Also, when labels are oriented such that the illumination source is reflected directly into the imager, the imager may fail to read properly due to uniform reflection washing out the desired image entirely, or reflection from a textured specular surface washing out one or more elements. This effect may cause reading of shiny labels to be problematic at particular reflective angles. In addition, labels oriented at extreme acute angles relative to the imager may not be readable.
The present inventor has therefore determined that it would be desirable to provide an imaging scanner that improves on these or other such limitations.